1. Field of the Invention
The invention relates to a device for operation of a high pressure discharge lamp. The invention relates especially to an operation device which comprises:                a superhigh pressure discharge lamp which is filled with at least 0.2 mg/mm3 of mercury and in which a pressure of at least 200 atm is achieved during operation; and        a feed device for the latter.        
2. Description of Related Art
Projector devices are generally of a type using a liquid crystal cell or using a digital light processor (DLP).
The type of projector device using a liquid crystal cell includes a single sheet type and a three-sheet type. In each type, the following takes place:                The radiant light from the light source is separated into three colors (R(ed)G(reen)B(lue)).        The light which corresponds to the video information is transmitted and regulated by a liquid crystal cell;        Afterwards, the three colors which have been transmitted by the cell are combined and projected onto the screen.        
On the other hand, in the type of projector device using a DLP, the following takes place:                The radiant light is emitted from the light source via a rotary filter in which RGB regions are formed by division onto a space modulation element (also called a light modulation device)—specifically a DMD element or the like) or the like by time division;        
Certain light is reflected by this DMD element (DMD—digital micro mirror device) and emitted onto a screen. Here, the expression “DMD element” is defined as an arrangement in which each pixel is covered with a few hundred million small mirrors at a time with light projection being controlled by controlling the direction of the individual small mirrors.
The DLP type, as compared to the liquid crystal type, has the advantage that the overall device can be small and simple because the optical system is simple and because it is not necessary to use as many as three liquid crystal cells.
The light source of the projector device is a high pressure discharge lamp with a high mercury vapor pressure. The reason for this is the following:
Because the mercury vapor pressure is high, light in the visible wavelength range with high intensity is obtained.
Furthermore, it is known that in such a discharge lamp with a high mercury vapor pressure, during operation, projections are formed on the electrode tips. For example, in JP patent disclosure document 2002-175890, the presence of these projections is regarded as a disadvantage and a technology is presented in which the projections are caused to disappear. Specifically, a technology is disclosed in which the frequency of rated operation maintains a lower frequency (for example, 5 Hz) of at least 1 second in which, in this way, the electrode surface is caused to melt and which is thus used to completely eliminate the projections.
Even if a high pressure discharge lamp (ultra-high pressure mercury lamp) has been operated as the light source of a projector device by the above described technology, the arc spot becomes unstable and so-called flicker occurs to a great degree. Flicker occurs especially clearly in a discharge lamp with an amount of added mercury of greater than or equal to 0.20 mg/mm3.